The extraction behaviour of copper(II) and nickel(II) with bis(2,4,4-trimethyl pentyl)dithiophosphinic acid has been studied at various parameters such as, pH, acidity, reagent concentration, equilibration period, solvent effect and effect of diverse ions. The copper(II) was quantitatively extracted from 0.5 M HCl with 5 x 10(-3) M Cyanex 301 and nickel(II) was extracted at pH 8.00 with 5 x 10(-3) M Cyanex 301. The brownish yellow copper complex absorbed at 440 nm while coloured complex of nickel showed maximum absorption at 340 nm. Both metals were separated from multicomponent mixtures. The proposed method was successfully employed for the determination of copper and nickel in real samples.